Re: [PATCH v9 11/11] Documentation: add documentation for 'git interpret-trailers'

From: Christian Couder <chriscool@tuxfamily.org>
Date: Apr 7, 2014, 18:58 UTC
Message-ID: <20140407.205800.839733420387302333.chriscool@tuxfamily.org>
In-Reply-To: <xmqq4n25nkt0.fsf@gitster.dls.corp.google.com>

From: Junio C Hamano <gitster@pobox.com>

Show 9 quoted lines

>
> Christian Couder <christian.couder@gmail.com> writes:
> 
>> First accepting both ':' and '=' means one can see the "git
>> interpret-trailers" as acting on trailers only. Not just on trailers
>> from the intput message and option parameters from the command line.
> 
> Sorry, you lost me.  What does "acting on trailers only" really
> mean?

It means that the command can seen as processing only trailers, (from stdin and from its arguments), sorry if I used the wrong verb.

Show 17 quoted lines

> Do you mean the command should/can be run without any command
> line options, pick up the existing "Signed-off-by:" and friends in
> its input and emit its output, somehow taking these existing ones as
> its instruction regarding how to transform the input to its output?
>
>> And second there is also a practical advantage, as the user can
>> copy-paste trailers directly from other messages into the command line
>> to pass them as arguments to "git interpret-trailers" without the need
>> to replace the ':' with '='. Even if this command is not often used
>> directly by users, it might simplify scripts using it.
>>
>> Third there is a technical advantage which is that the code that
>> parses arguments from the command line can be the same as the code
>> that parses trailers from the input message.
> 
> I do not see these two as valid arguments to make the command line
> more complex to the end users

I don't think that it makes the command more complex to the end users.

> ---who now need to know that only this
> command treats its command line in a funny way, accepting a colon in
> place of an equal sign.

It accepts both. So if they think that it is like a regular command, which uses '=' for (key, value) pairs, it will work, and if they think it works on trailers, which use ':' for (key, value) pairs, it will also work.

Show 14 quoted lines

> A different way to sell a colon, e.g.
> 
>     Consider the instruction sed takes on its command line.
>     (e.g. "sed 's/frotz/nitfol/' <xyzzy").  In the most general
>     form, you would always give it as the value of an '-e' option
>     (e.g. "sed -e 's/frotz/nitfol' <xyzzy"), but you are allowed to
>     be loose in limited occassions.  "Key:value" is like that, and
>     in the most general form, it actually needs to be spelled as
>     "-e 'Key:value'".
> 
> is possible, but I do not think it is a particularly good analogy,
> because what you have as the alternative is "Key=value", and not
> "-e 'Key:value'", or "--Key=value" (the last would probably be the 
> most natural way to express this).

The analogy that I would use is rather that Perl lets people use 's:foo:bar:' as well as 's=foo=bar=' instead of 's/foo/bar/' if they prefer.